1. Field of the Invention
The present invention relates to a driving mechanism for a narrow width crochet knitting machine which is a narrow width warp knitting machine including a compound knitting needle composed of a combination of a hook-like knitting needle and a slider for opening/closing a hook opening of the hook-like knitting needle, and a guide needle for a warp knitting yarn and a weft in-laid yarn. Particularly, it relates to a driving mechanism for controlling an operating timing and stroke of the hook-like knitting needle and the slider. More particularly, the present invention relates to a driving mechanism of a narrow width crochet knitting machine, which can relatively operate the hook-like knitting needle and the slider at a proper timing and stroke without shakiness, and can form various knitted loops at a high speed.
2. Description of the Related Art
Conventionally, in this type of warp knitting machine, with the aforesaid high speed, a Karabiner needle which is one of so-called "beard needle" has been used, as disclosed in U.S. Pat. No. 4,417,455. This knitting needle merely form a knitted loop from one direction, and a weft in-laid yarn is not caught by the knitting needle even in a high speed; and thus, proper weft insertion can be carried out. However, in general, the knitting needle can not form an open loop, and forms only closed loop. For this reason, since various knitted loops are required in recent years, it is difficult to form various knitted loops by using the general crochet knitting machine. As a result, there are many cases of using a "compound knitting needle" comprising a hook-like knitting needle and a needle-like slider for opening and closing an opening of the hook-like knitting needle in place of the aforesaid knitting needle.
By the way, a knitting mechanism by the above compound knitting needle is as shown in FIG. 7(A) to FIG. 7(D). First, a hook-like knitting needle 1 hooks a warp knitting yarn 2, and then, with a needle-like slider 3 closing a hook opening 1a of the hook-like knitting needle 1, both the slider 3 and the knitting needle 1 are retracted to the most retracting position on a needle bed fixed on a machine frame (not shown) (see FIG. 7(A)), and thereafter, the hook-like knitting needle 1 independently advances as the slider 3 is not moved (see FIG. 7(B)). In order to form a next knitted loop on the most advancing position, the warp knitting yarn 2 runs over the hook opening 1a of the hook-like knitting needle 1 by a swinging operation of a warp knitting yarn guide needle 4, and then, is hooked on the hook-like knitting needle 1 (see FIG. 7(C)).
At this time, the slider 3 is advanced, and then, closes the hook opening 1a of the hook-like knitting needle 1 so that the warp knitting yarn 2 is not released from the hook opening 1a (see FIG. 7(D) ). When closing by the slider is completed, the hook-like knitting needle 1 and the slider 3 begin to retract together, and then, are returned to the position as shown in FIG. 7(A).
The plurality of hook-like knitting needles 1 and sliders 3 are individually repeatedly operated at the aforesaid timing, and then, knitted loops are successively formed, and thus, a desired warp knitted fabric is knitted. In the crochet knitting machine, a plurality of weft in-laid yarn guide bars (not shown) are arranged longitudinally above a tip end of the warp knitting yarn guide needle 4. Each weft in-laid yarn guide bar is transversely reciprocated, and then, a plurality of weft in-laid yarn guide needles (not shown) attached to the weft in-laid yarn guide bar are transversely reciprocated, and thus, many weft in-laid yarns (not shown) are successively inserted into a predetermined warp knitted loop.
As described above, in the knitting mechanism of the compound knitting needle in this type of narrow width crochet knitting machine, it is very important that the hook-like knitting needle and the slider are operated at a proper timing. Unless the hook-like knitting needle and the slider are operated within a range of proper reciprocating stroke, loop skipping is much generated, or an unnecessary weft insertion to a knitted loop is made; as a result, it is impossible to carry out desired knitting. In particular, the aforesaid problem frequently arises as the machine is run in high speed.
In order to solve the above problem, a driving mechanism of a compound knitting needle, which is adaptable to a high speed in some degree, has been developed. For example, European Patent Publication No. 0302209A1 discloses a driving mechanism of a compound knitting needle, in which the driving mechanism operates as follows. As shown in FIG. 4, the plural hook-like knitting needles 1 are fixed to a needle bar 7 at their rear ends, and the plural needle-like sliders 3 are fixed to a slider bar 8 at their rear ends, and the needle bar 7 and the slider bar 8 are disposed independently from each other so as to be reciprocated. The needle bar 7 and the slider bar 8 are fixed to a front end of each of two rods 7a and 8a. On the other hand, two rotary plane cams 9a and 9b are attached to a main rotary shaft as being arranged in parallel, and further, rolling elements 7b and 8b attached to the rear ends of rods 7a and 8a are elastically abutted against respective cam surfaces of the two rotary plane cams 9a and 9b.
In the driving mechanism of the compound knitting needle, when a main shaft is rotated, the rotary plane cams 9a and 9b are rotated, and then, the rolling elements 7b and 8b elastically abutted against respective cams 9a and 9b follow, and thus, the rods 7a and 8a, that is, the needle bar 7 and the slider bar 8 are reciprocated at a timing and stroke independently from each other. The timing and stroke of reciprocation at this time are determined by a cam curve of respective rotary plane cams 9a and 9b.
For example, Japanese Patent Publication No. 4-44025 discloses another driving mechanism of the above (compound knitting needle. In this driving mechanism, as shown in FIG. 5, the needle bar 7 and the slider bar 8 are reciprocated via a link mechanism at a predetermined timing and stroke. More specifically, the needle bar 7 is reciprocated by a first crank pin 71 which is located on an eccentric position of a rotating disc rotating when the main rotary shaft is rotated, via a first link 72. On the other hand, respective one ends of second and third links 83 and 84 are supported on crank pins 81 and 82 of second and third rotating discs rotating when the main rotary shaft is rotated, and the other ends of second and third links 83 and 84 are connected by means of a fourth link 85. The rod 8a fixed to the slider bar 8 at its front end is rotatably supported at its rear end on the central point of the fourth link 85, and a combined operation of the second and third links 83 and 84 by the rotation of the second and third crank pins 81 and 82 rotating synchronously with a rotation of the main rotary shaft, is converted into a reciprocation of the rod 8a via the fourth link 85. Thus, the needle-like slider bar 8 is reciprocated at the predetermined timing and stroke as described above.
These driving mechanisms individually have merits and demerits. For example, in the case of determining the above operation timing and stroke of the needle bar and the slider bar by the rotary plane cam, it is possible to carry out a control with a high accuracy by setting an ideal cam curve. However, when a speed is high, for example, it exceeds 1200 r.p.m., the rolling element, which is a cam driven element, can not follow a rotation of cam; for this reason, wear between contacting members or jumping is frequently generated. As a result, even if cam surface machining having an ideal cam curve is made, the timing is shifted in the operation between the hook-like knitting needle and the slider, or their operation become irregular, and loop skipping is generated. Therefore, it is impossible to obtain a desired knitted tape.
Meanwhile, according to the aforesaid driving mechanism by combining a crank and a link, the mechanism has almost no shakiness on its mechanism, and is adaptable to a high speed as compared with the driving mechanism using the rotary plane cam. Moreover, a reciprocating operation of the hook-like knitting needle is a sine curve of 360.degree., and its acceleration and stroke are determined solely by an arm length of the first crank and a link length; therefore, it is possible to readily set the operation timing and stroke. On the other hand, a reciprocating operation of the slider is based on a combined operation of the second and third cranks and second to fourth links. Thus, their acceleration and stroke are variously modified by an arm length of the second and third crank, a phase difference between the second and third crank pins, each length of the second to fourth links. However, there are many factors of giving an influence to the operation timing and stroke, and the structure is complicated; for this reason, it is difficult to set a highly accurate motion curve.
The following problem arises in either case of the above driving mechanisms. Particularly, with this type of narrow width crochet knitting machine, for example, in the case of manufacturing a slide fastener stringer continuously in which an engaging element made of a monofilament is knitted continuously in a tape at the time of knitting the tape, and thus, in addition to the above knitting timing, there is a need of knitting a thick monofilament by weft insertion; for this reason, the aforesaid operation timing and stroke of the compound knitting needle must be further strictly controlled. Therefore, it is impossible to manufacture the above stringer at a high speed.